Electric switch



May 2, 1950 w. G. BOURNE ELECTRIC swI'rcH Filed May 5, 1948 Patented May2, 1950 ELECTRIC SWITCH William George Bourne, London, England, assignorto Rotax Limited, London, England Application May 5, 1948, Serial No.25,192

- In Great Britain May 8, 1947 2 Claims.

This invention relates to electric switches of the tumbler type. Theseswitches are known in many different forms, and are adapted to operatein a number of different ways, all depending on the actuation of apivoted finger lever. In some switches the movement of the finger leverfrom one limiting position to another serves to open or close a singleelectric circuit, or to open one circuit and close another. Or, with thelever normally occupying a central position, control of either of twocircuits is effected by moving the lever to one side or the other of thesaid position. Moreover, in some switches the lever is held by theaction of a spring in the position to which it has been moved, in othersit is automatically returned by a spring to its initial position whenthe finger lever is released. Hitherto the provision of a range ofswitches individually capable of operating in any of the above-mentionedor other analogous ways, has involved much multiplication of componentparts and consequent complication of manufacturing operations. Anobviously desirable condition from consideration of economy ofmanufacture is that all the switches in a given range should employ asmany similar components as possible, and the object of the presentinvention is to enable this condition to be met in a convenient andsatisfactory manner.

In the accompanying drawings,

Figure 1 is a side sectional elevation of an electric switch of thetumbler type constructed in accordance with the invention and arrangedfor the control of either of two circuits by moving the finger lever toone side or the other of a central or neutral position; i l

' Figure 2 is an end sectional elevation of the switch'taken on thecentre line' of Figure 1; v.

Figure 3 is a side elevation of a part of the switch mounting androcker, with the cam piece omitted; I

Figure v4 is an elevation, partly in section, of a portion of the switchmechanism of Figure 1, provided with a modified form of cam piece;

Figure 5 is a view similar to Figure 4 showing another modified form ofcam piece;

Figure 6 is a view similar to Figure 5 showing a further modified formof cam piece.

In carrying the invention into eii'ect according to one convenient modeas illustrated in Figures 1, 2 and 3, there is provided a sheet metalmounting l for carrying the finger lever and rocker of the switch. Themounting is of deep U-section having a pair of parallel sides which arewider at their upper ends, and which at their lower ends are joined byan integral cross part g, 7 At about 2 the mid point of each of thesides there is formed an aperture 3.

The rocker is a sheet metal part having a pair of arms 4 extending inopposite directions from its central portion, the outer end of each'armserving as or having secured to it a contact piece 5. The central part 6of the rocker is also 01 U-section and the upper ends of its sides arebent over at l (or are provided with pins) to engage the apertures 3 inthe mounting l and serve as pivotal connections between the rocker andmounting, the rocker being located between the sides of the mounting asshown in Figure 2.

The finger lever may be of any convenient construction. Preferably itconsists in part of a metal stem 8 which has a cylindrical bore 9extending for a convenient distance from itsinner end, and in this boreis accommodated a helical spring I0 which bears on a metal ball I Iinserted in the lower end of the bore, the ball serving as the abutmentrequired to co-operate with the cam piece to be hereinafter described.This metal stem is encased from about its centre to its outer end by asheath !2 of thermoplastic or analogous material, and the inner end ofthe sheath has moulded. on it a spherical part l3 adapted to occupy acorresponding seating M in a cover piece I 5. The cover piece isprovided also with a slot l6 through which the outer end of the lever 8extends. The central and inner parts of the'leverlie between the sidesof the mounting I, and the central part is connected to the mounting bya pair of coaxial pivot pieces 41. The mounting l is secured to thecover l5 by screws l8.

On the rocker is mounted a separately made cam piece I 9, and it is theform of this piece that determines the mode of action of the switch. Thecombination of mounting, finger leverand rocker, serves for any switchin the range to be manufactured, the only component which is differentfor different switches being the cam piece. If itis required to providea switch of the kind in which the finger lever occupies a midpositionwhen the switch is open, and in which movement of the lever to eitherside of this position serves to close one or the other of a pair ofcircuits to be controlled by the switch, .the cam piece consists of afiat metal piece as shown in Figures 1 and 2 having at the centre of itsupper edge a recess 20 adapted to be engaged by the spring loaded ballll above mentioned on the finger lever 8, and having at the oppositesides of the recess a pair of similar andupwardly inclined straightedges 2| on which the ball can act when the finger lever is moved. Theunder edges 22 ofthecam piece are adapted to seat firmly on the uppersurfaces of the arms 4 of the rocker, and preferably it is provided witha central projection 23 which occupies a recess between the said arms,the cam piece being secured to the rocker by a rivet, cotter or the like24 inserted through it and through the sides of the rocker 5. This campiece is such that with movement o f' the finger lever to either side ofcentral position the rocker is caused to move about its pivotalconnection with the mounting under the action of the spring loaded ballI l on one of the inclined edges 2| of -t-heoam piece, and these edgesare so designed that the rocker and the finger lever wili be 'movedautomatically to circuit opening position as soon as the finger lever isreleased, the rocker then being held by the engagement of the ball withthereoess 20 in the cam piece.

As regards the remainder of the switch this may take a variety of forms.In the example illustrated there provided an insulating base 25 carryinga pair of contacts 26 for era-operating with the rocker "contacts 5. Ihebase may be secured to the mounting l by ascrew but preferably andasshow-n-a metal member '2! is moulded into the base and hasaicylindrical'part =28 which riveted over a hole in the cross part 2 orthe mounting. The cover piece I *is extended to form a wall -29 whichencloses the base, and to the lower end'of this wall a second coverpiece -35 is'secured by a screw 34 to enclose the underside of the baseand the terminal connections provided on the base.

It will be seen that with the (arrangement described the finger levermay occupy a middle :or neutral position, or-may be moved to one side orthe other to close either of two circuits, and will return automaticallyto said middle or neutral position as soon as positive pressure onthefinger lever 'is removed. I V

If it is required to provide a two way switch such that one of a pair ofcircuits to be controlled is closed when the other is open, the campiece described in the previous example is replaced by a d'iiierent campiece as shown in Figure 4. The cam piece 32 for this purpose is similarto the previously described cam piece l9 except for the shapeo'f itsupper edge which has at its centre an inverted V-ridge '33 and .astraight edge 34 which is given 'a slight upward "inclination at eitherside of "the V-r'idge. With this foam piece in position the finger levercan only rest in one or other of inclined positions as shown in Figure'4, i. e. one '01 other of *th'e'circuits controlled by'the contacts 1'6will alxxnrys *be closed. The construction of remainder cf 'the switchis the same as "described for the previous example.

For some purposes it is required that the lever shall occupy a centralposition when the switch is'open, and that when moved in'one directionfrom that position it shall close one of a pair of associated circuits,this circuit remaining closed until opened by positive movement of thelinger lever in the reverse direction, but as regards the other circuitit is required that when closed it can remain closed only so long as theuser exerts pressure "on the finger lever. This requirement is'met bythe use of a modified form of cam piece as "shown in Figure 5. The campiece 3% is similar so far asone half of it is concerhed to the campiece of Figures 1 to 3; Thus there is provided a central depression 36and on one side of it an inclined surface 31 arranged so when depressedthe ball I] of the finger lever the latter will remain in position withthe contacts closed only so iong 'as positive pressure is exerted on thefinger lever, the finger lever and rocker returning automatically tocircuit opening position as soon as such pressure is removed. On theother side of the depression 36 there is provided a gently inclinedsurface 38 (similar to the inclined surfaces 34 shown in Figure 4) sodisposed that its interaction with the spring loaded 'ba'll H causes thefinger lever and rocker to re- "main in position with the contactsclosed until released by positive actuation. The construction or theremainder of the switch is the same as describedin connection withFigures 1 to 3.

For other purposes it is required that the switch shall remain incircuit closing position when the finger lever is moved to either sideof the central position. This requirement is met by the use or themodified form of cam piece shown in Figure 6. The cam piece 39 issimilar to the previously described cam pieces except for the shape ofthe upper surface thereof. There is provided a central depression 40 anda pair of gently in- =clined surfaces 4 pm either side thereof, theseeeing disposed in a similar inannerto the surface -38 of the previouslydescribed example. The operation of the switch will be clear from theio'regoing description.

From the foregoing it will be seen that any of a variety of requirementscan *be met by the use of an appropriately shaped cam piece, and it isto he understood that the invention is not limited to the examplesspecified. Further whilst in the Fioregoihg there has been described theapplication of the invention to double acting switches, it will beunderstood the same components may he used in single acting switches,the rocker being then provided with a contact 'at one only.

By this invention the manufacture of a range of different tumblerswitches 'can be greatly simplified, as most of the components are thesame @01- an the switches in the range, the only (or principal)component which is different in the different switches and whichdetermines the action of the switch being the cam piece.

The invention is not, however, restricted to the particular constructionof mounting, finger lever, rocker and 'cover piece above described, asthese and other features may he modified to suit different requirements.

Having thus described my invention what I "claim as new and desire tosecure by Letters Patent is: a

-1. An electric switch having .in combination a base piece, at least onefixed contact on said base piece, a coverpiece, a mounting of deepLiform secured at "its o en end to cover piece at its plos'ed end tosaid 'base piece, a finger lever extending through an aperture in saidcover piece and carried by said mounting, -a movable contact piece inthe form of a rocker also carriedhbyfsaid mounting and arranged to co-.operate with said fixed contact, a cam piece made separately from andrigidly'secured to said rocker so as to be movable therewith butincapable of movement relatively thereto, and a spring loaded abutmentpiece slidably supported by -the inner end of said finger lever andarranged in "contact with sa-id cam piece so "that movement of "saidfinger lever "is accompanied by movement 01 said cam piece and rocker.

2. An electric switch as claimed in claim 1, in which said rockercomprises a pair o'f contact arm's extending in opposite directions fromand formed integrally with a central U shaped part which at its upperends is provided with lateral projections engaging apertures in thesides of said mounting.

WILLIAM GEORGE EoURNE.

REFERENCES CITED The following references are of record in the the ofthis patent:

Number 6 UNITED STATES P ATENTS

